A study of charm meson production in semileptonic B decays

The results of a study of charm meson production in semileptonic B hadron decays are presented. Based on a sample of 1.72 million hadronic Z0 decays the following product branching ratios (averaged over electrons and muons) are obtained:$$\begin{gathered} B(b \to D^ + \ell X) \cdot B(D^ + \to K^ - \pi ^ + \pi ^ + ) \hfill \\ = (1.82 \pm 0.20 \pm 0.12) \times 10^{ - 3} , \hfill \\ B(b \to D^0 \ell X) \cdot B(D^0 \to K^ - \pi ^ + ) \hfill \\ = (2.52 \pm 0.14 \pm 0.17) \times 10^{ - 3} \hfill \\ B(b \to D^* \ell X) \cdot B(D^{* + } \to D^0 \pi ^ + ) \cdot B(D^0 \to K^ - \pi ^ + ) \hfill \\ = (7.53 \pm 0.47 \pm 0.56) \times 10^{ - 4} \hfill \\ \end{gathered} $$ where the first error is statistical and the second systematic.The results of a search for the narrow P-wave charmed mesons, (DJ), in semileptonic B decays are also reported. Using the decay channels DJ0→D+π−, DJ0→D*+π− and D+J→D0π+ we observe a total signal of 44±8−7+3 DJ0 and 48±10−6+3 DJ+ events. This is the first evidence for semileptonic B decays to charged P-wave charm states. The observed signals also provide evidence for the production of both pseudovector and tensor P-wave charmed mesons in semileptonic B decay. Together these modes are estimated to make up 34±7% of charmed semileptonic B0 and B+ decays.